As the candidates approach the May 4 finish line in Panama’s presidential race, the winner remains unclear. There are seven competitors, but three lead the pack: José Domingo Arias of the ruling party Democratic Change (CD), former Panama City Mayor Juan Carlos Navarro of the Democratic Revolutionary Party (PRD), and Vice President Juan Carlos Varela of the Panameñista Party (PP). Earlier polls gave Arias a wider lead, but some of the final surveys show that lead shrinking, as shown by poll numbers below by firms Ipsos/Panamá Opina, Dichter & Neira, and Quantix. (The three polls estimate a margin of error of roughly +/-2 percent.).

So what’s behind the tightening race?

Panama only holds one round of voting, meaning the candidate declared the victor on May 4 will take office for a five-year term on July 1. Presidents serve one five-year term, and must wait out two subsequent terms before seeking reelection.

Therein lies one of the controversies of this election: Arias’ running mate is Marta Linares, wife of current President Ricardo Martinelli, raising concerns he will keep playing a role in Panamanian politics and prompting opponents to appeal to the Supreme Court regarding the constitutionality of the first lady’s candidacy. The country’s electoral tribunal determined that there were no obstacles to her being on the Arias ticket.

In fact, some see the election as a referendum on Martinelli’s presidency, which was marked by high economic growth, large-scale infrastructure projects such as the Panama Canal Expansion, and a real estate boom. However, as the supermarket magnate’s term draws to a close, growth is slowing, concerns over public spending are on the rise, and the president faces mounting corruption allegations. And in the final days before the election, Panama Canal construction workers opted to strike in demand of a wage increase. Meanwhile, Arias, who served as housing minister in the current administration, finds himself making the case that he will not be under Martinelli’s influence should he win.

But the opposition candidates aren’t free of Achilles heels either. Both the PRD's Navarro and PP's Varela have found themselves facing corruption rumors. The Dichter & Neira poll pointed out that it’s likely that Sunday’s winning candidate will fail to clear 40 percent of the vote, meaning a weak mandate—particularly when compared to Martinelli’s landslide win in 2009. Ex-President Martin Torrijos commented on the electoral race this week by saying “it will be remembered as a campaign of regression.” Not only that, but recent days have shown troubling signs for electoral transparency, with the website of news outlet TVN experiencing cyber attacks that drew the condemnation of the Inter American Press Association.